Does Jack realize the killing of Simon and Piggy?
Jack tells the boys, in chapter 10, that what they saw and attacked was the beast because the beast could take on any form it wanted. He justifies the killing of Simon in this way. He even warns the boys that the beast may come at them again in disguise, so they should offer up a sacrifice to the mountain (and the beast) whenever they killed a pig by putting the pig's head on a stick. He doesn't dwell on the issue, dismissing it as something not important enough to say any more about. At the end of chapter 11, when Roger descends from the rocks to where Jack is, Jack realizes that Roger pushed the rock onto Piggy on purpose. Jack can see what he's unleashed in the sadistic Roger, but again, he dismisses it. Jack cannot dwell upon the evil he's let out of the others probably because to dwell on it would make him face the true horror - the true beast and he does not have the strength of will to do that. Jack is a coward, so rather than face the evil, he hides from it. He paints his face, putting on his mask, to hide from the evil. Jack knows that he and the others have killed Simon and Piggy, but he hides the thoughts from his conscious mind in the same way he hides his face.